Athlon II X4 640 on an ASRock 870 Extreme3. This is the board that over-volted the 970 to 1.60v... well it was a BIOS setting... Load Line Calibration. When set to Auto it does it's own thing... when set to Normal it uses the BIOS setting. It's nice to know what the problem was and credit goes to Rajinder Gill who had the same issue on an ASRock 890FX in this review...